Two way locking rotary drive clutch assembly

ABSTRACT

A-way locking rotary drive clutch assembly for actuating an adjuster mechanism on an automotive vehicle seat including a cylinder ( 30 ) fixedly secured to the vehicle seat and a mobile flange ( 40 ) rotatable journaled to the cylinder and fixedly secured to an input shaft ( 18 ) for externally actuating the adjuster mechanism. The cylinder includes a cylindrical bearing surface. The clutch assembly includes a plurality of cams ( 50, 52 ) enactable with the bearing surface to prevent rotation of the mobile flange relative to the cylinder. The cams are rotatable assembled to the mobile flange for moving in and out of engagement with the bearing surface. The cams are biased into engagement with the bearing surface. A handle body ( 60 ) journaled to the cylinder includes a plurality of teeth engagable with teeth on the mobile flange. Tabs ( 62 ) extend from the handle body to move the cams out of engagement with the bearing surface during rotation of the handle body relative to the mobile flange. The spacing between the teeth of the mobile flange and handle body is greater than the spacing between the tabs and respective cams so that the cams disengage the bearing surface of the cylinder before the teeth of the mobile flange and handle body engage.

RELATED APPLICATION

This patent application is a §371 of PCT/US03/03667, filed on Feb. 6,2003, which claims priority to and all the benefits of U.S. ProvisionalPatent Application No. 60/354,829 filed on Feb. 6, 2002.

FIELD OF THE INVENTION

The invention relates to a friction-type clutch mechanism for actuatinga rotary input shaft of an adjustment mechanism for a seat of a motorvehicle. More particularly, the invention relates to a clutch assemblyactuate a rotary input shaft to move an adjuster mechanism in twodirections using a reciprocating input device.

DESCRIPTION OF THE RELATED ART

Automotive vehicles include seat assemblies for supporting occupantswithin the vehicle. Seat assemblies typically include a seat cushion forsupporting a seated occupant and a seat back for supporting the uppertorso of the occupant. To accommodate a wide range of occupant shapesand sizes, seat assemblies commonly incorporate various adjusters tomanipulate the shape of the seat back or seat cushion, to adjust theorientation of the seat back relative to the seat cushion, and to adjustthe position of the seat assembly within the vehicle with respect togenerally fixed pedal and steering wheel locations. For example, it iswell known in the seating art to incorporate a manual height adjusterassembly between the seat cushion and the vehicle floor to allow theoccupant to manually adjust the height of the seat cushion or the entireseat assembly relative to the vehicle floor. To adjust the height of theseat assembly, the occupant actuates a rotary knob or lever armextending outwardly from the height adjuster assembly. It is common fora height adjuster assembly to include a clutch mechanism between theknob or lever arm and the height adjuster assembly to prevent the weightof the occupant or vehicle accelerations from back-driving the heightadjuster assembly. However, current height adjuster assemblies utilizecomplex, or otherwise expensive, spring friction or roller ball typeclutch designs.

Accordingly, it remains desirable to provide a simple, low-cost clutchdesign for use in conjunction with adjuster mechanisms in the seatassembly, such as height adjuster assemblies.

SUMMARY OF THE INVENTION

A clutch assembly actuates an input shaft of an adjuster mechanism in aseat for a motor vehicle. The clutch assembly includes a cylinder thatis fixedly secured to the seat. The cylinder includes an inner wall. Theclutch assembly also includes a mobile flange that is fixedly secured tothe input shaft for rotating the input shaft with respect to thecylinder. A cam mechanism selectively engages the inner wall of thecylinder to prevent movement of the mobile flange and the input shaftrelative to the cylinder. The cam mechanism is operatively assembled tothe mobile flange for movement in and out of engagement with thecylinder. The clutch assembly also includes an actuator operativelyinterconnected to the cylinder for movement relative to the mobileflange. The actuator includes a tab engagable with the cam duringmovement of the actuator relative to the mobile flange to move the camout of engagement with the cylinder to release the adjuster mechanismallowing movement of the seat.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the invention will be readily appreciated as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a side view of a seat incorporating a clutch assemblyaccording to one embodiment of the invention;

FIG. 2 is a side view of the clutch assembly;

FIG. 3 is a cross-sectional end view taken along lines 3—3 of FIG. 2;

FIG. 4 is a perspective view of a second embodiment of the inventionsecured to an adjuster mechanism;

FIG. 5 is an exploded perspective view of the second embodiment of theinvention;

FIG. 6 is a side view taken along lines 6—6 of FIG. 5;

FIG. 7 is a side view taken along lines 7—7 of FIG. 5;

FIG. 8 is a side view of the second embodiment showing the clutchassembly in a non-actuated state;

FIG. 9 is a side view showing a ratchet assembly of the secondembodiment in an actuated state;

FIG. 10 is a side view of the second embodiment with the clutch assemblybeing actuated; and

FIG. 11 is a side view of the second embodiment with the clutch assemblyactuating the input shaft of the adjuster mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a seat 10 is shown for supporting an occupant abovea floor 5 within a motor vehicle, represented by the floor 5. The seat10 includes a clutch assembly 20 according to the invention. Forillustrative purposes, the clutch assembly 20 is discussed below used inconjunction with a seat height adjuster mechanism. It should beappreciated by those skilled in the art that the clutch assembly 20 iseasily adaptable for use with other types of mechanisms on the seat 10utilizing a rotary input shaft, such as seat back recliner mechanisms orpivoting armrest assemblies.

The seat 10 includes a seat cushion 12 and a seat back 14 pivotallyinterconnected to the seat cushion 12 for movement between a pluralityof reclined positions. A height adjuster mechanism 16 extends betweenthe seat cushion 12 and the vehicle floor 5. The height adjuster 16allows the occupant to adjust the height of the seat 10 relative to thevehicle floor 5. The adjuster mechanism 16 is biased in a locked statewherein the height of the seat 10 is maintained. The adjuster mechanism16 is selectively movable from the locked state to an unlocked state toallow the height adjustment of the seat 10. A rotating input shaft 18 isoperatively coupled to the adjuster mechanism 16 for actuation of theadjuster mechanism 16 to move the seat cushion 12 between its variouspositions of height. The input shaft 18 extends out beyond the end ofthe seat cushion 12.

A lever 19 extends outwardly from the terminal end of the input shaft 18to facilitate actuation of the adjuster mechanism 16. Described ingreater detail below, the clutch assembly 20, disposed between the inputshaft 18 and the lever 19, prevents back driving of the adjustermechanism 16 by weight of the occupant or vehicle accelerations, whilealso transferring occupant input applied upon the lever 19 to the inputshaft 18.

Referring to FIGS. 2 and 3, the clutch assembly 20 includes a cylinder30 fixedly assembled to the seat cushion 12, or alternatively, to aportion of the adjuster mechanism 16 movable with the seat cushion 12.The cylinder 30 includes an inner wall 32 aligned with the input shaft18. The terminal end 34 of the input shaft 18 projects axially throughand beyond the cylinder 30 presenting a mounting surface 22. A mobileflange 40 rotatably journaled to the cylinder 30 extends between agenerally periphery 42 aligned axially with the input shaft 18 and aninner bore surface 44 adapted to receive the mounting surface 22 of theinput shaft 18 therethrough in a keyed, press fit relationship forrotational movement therewith. Alternatively, the mobile flange 40 isfixedly secured to the mounting surface 22 by welding, or the othersuitable fixing means. Thus, rotating the mobile flange 40, which isfixedly secured to the input shaft 18, actuates the adjuster mechanism16. A plurality of outwardly extending teeth 46 extends radiallyoutwardly from the periphery 42.

A pair complementary of first and second cams 50, 52 are disposedbetween the cylinder 30 and mobile flange 40. Each of the first andsecond cams 50, 52 are rotatably assembled to a respective pivot pin 45,47 extending axially from the mobile flange 40 for movement into and outof engagement with the inner wall 32 of the cylinder 30. When engagedwith the inner wall 32, the first and cams 50, 52 are wedged between therespective pivot pin 45, 47 and the inner wall 32. While so positioned,friction between the first 50 and second 52 cams and the inner wall 32prevents clockwise and counterclockwise rotation, respectively, of themobile flange 40 relative to the cylinder 30, as viewed in FIG. 2.

First and second biasing members 54, 56 act between the mobile flange 30and the first and second cams 50, 52, respectively, for rotatablybiasing the first and second cams 50, 52 towards engagement with thebearing surface 32.

The clutch assembly 20 includes an actuator 60 for moving the first orsecond cams 50, 52 and rotating the mobile flange 40 thereafter toactuate the adjuster mechanism 16. More specifically, the actuator 60includes a cylindrical plate 61 having a tab 62 projecting axially outfrom the actuator 60 and between the first cam 50 and second cam 52 formoving the first cam 50 or second cam 52 away from the inner wall 32during counterclockwise or clockwise rotation, respectively, of theactuator 60, as viewed in FIG. 2. The tab 62 is generally evenly spacedapart from each of the first 50 and second 52 cams by a predetermineddistance X, as indicated in FIG. 2.

The actuator 60 further includes a plurality of inwardly extending teeth64 engagable with the outwardly extending teeth 46 extending from themobile flange 40 for rotating the mobile flange 40 during rotation ofthe body 60. Each inwardly extending tooth 64 of the actuator 60 isgenerally evenly spaced apart from an adjacent outwardly extending tooth46 of the mobile flange 40 to create a gap Y, as indicated in FIG. 2.The gap Y is greater than the predetermined distance X, so that thefirst 50 or second 52 cams are disengaged with the inner wall 32 beforethe inwardly extending teeth 64 on the actuator 60 engage the outwardlyextending teeth 46 on the mobile flange 40 to rotate the mobile flange40 counterclockwise or clockwise, respectively, relative to the cylinder30. Alternatively, the body 60 is assembled in a keyed relationship withthe mobile flange 40 for driving the same and is movablecounterclockwise or clockwise relative to the mobile flange 40 throughthe distance Y before tab 62 engages the first cam 50 or second cam 52,respectively.

The lever 19 extends from the actuator 60 for facilitating manualactuation of the adjuster mechanism 16 via the clutch assembly 20.Alternatively, the lever 19 may be replaced by using a knurled actuator60. A third biasing member 66 extends between the mobile flange 40 andthe actuator 60 to maintain the distance Y between the outwardlyextending teeth 46 and the inwardly extending teeth 64.

In operation, engagement of the first 50 and second 52 cams with theinner wall 32 prevents back driving of the clutch assembly 20 via theinput shaft 18. For example, the weight of the occupant upon the seatcushion 12 or accelerations of the vehicle due to road input transferredthrough the input shaft 18 would not cause rotation of the mobile flange40 relative to the cylinder 30. The actuator 60 is rotatedcounterclockwise, for example, to actuate the adjuster mechanism 16, andthereby, lift the seat 10. The tab 62 moves the first cam 50 out ofengagement with the bearing surface 32 before the inwardly extendingteeth 64 on the actuator 60 contact the outwardly extending teeth 46.With the first cam 50 disengaged with the inner wall 32, the mobileflange 40 is freely movable in the counterclockwise direction relativeto the cylinder 30. The mobile flange 40 begins to rotatecounterclockwise when the inwardly directed teeth 64 engage theoutwardly extending teeth 46. The input shaft 18 rotatescounterclockwise with the mobile flange 40, thereby actuating theadjuster mechanism 16. Once the desired adjustment is made, the firstcam 50 is allowed to re-engage the bearing surface 32 of the cylinder 30under the bias of the first biasing member 54. The third biasing member66 moves the actuator 60 clockwise relative to the mobile flange 40until each of the outwardly extending teeth 46 are spaced from theinwardly extending teeth 64 by the gap Y. The operation is similar forclockwise rotation of the actuator 60 to lower the seat 10. The tab 62moves the second cam 52 out of engagement with the inner wall 32 of thecylinder 30 to allow clockwise rotation of the mobile flange 40, andultimately the input shaft 18, relative to the cylinder 30. Once desiredadjustment is complete, the second cam 52 is allowed to re-engage thebearing surface 32 under the bias of biasing member 56 in order toprevent further rotation of the mobile flange 40 relative to thecylinder 30. The third biasing member 66 moves the body 60counterclockwise relative to the mobile flange 40 until each of theoutwardly extending teeth 46 are spaced from each of the inwardlyextending teeth 64 by the gap Y.

Additional cams 50′, 52′ engagable with the inner wall 32 and rotatablyassembled to the mobile flange 40 may be added to improve load capacityand performance of the clutch assembly 20. Accordingly, another tab 62′on the body 60 and biasing members 54′, 56′ are added to actuate theadded cams 50′, 52′ in the manner described above. Preferably, the addedcams 50′, 52′ are arranged to act on opposing sides of the inner wall 32with respect to the first 50 and second 52 cams to minimize vibrationsor play in the clutch assembly 20 due to clearances related todimensional variation in manufacturing between the movable parts of theclutch assembly 20.

A second embodiment from that shown in FIGS. 2 and 3 is shown in FIG. 5,wherein elements of the alternative embodiment similar to those in thefirst embodiment are indicated by reference characters offset by 100.The clutch assembly 120 includes a lever 119 that may be moved from itsnon-actuated state and positions clockwise and counterclockwise thereto.These positions are limited by stops that engage a spring 124 havingends 126, 128 which generally prevent the lever arm 119 from moving pasta particular position in the clockwise position and the counterclockwiseposition, respectively, as shown in FIG. 5. The lever 119 is secured tothe actuator 160. The spring 124 is seated within the actuator 160.Disposed adjacent the spring 124 is a race 138 having a plurality ofball bearings 148 that aid in the smooth movement of the actuator 160and the lever 119.

In this embodiment, the cylinder 130 includes an end plate 158 thatdefines a seat within which the mobile flange 140 is able to rotate.Extending out from the cylindrical plate are a pair of tabs 162. Each ofthe tabs 162 include a pair of drive abutments 163 which extendoutwardly from the tabs 162. The drive abutments 163 will be discussedin greater detail subsequently. The end plate 158 includes first 165 andsecond 167 pawl spring cam surfaces. The end plate 158 defines a spacethat houses two pawls 168, 169, each having a pawl spring 170, 171.

Referring to FIG. 6, a drive arm 172 is shown keyed to the input shaft118. The drive arm 172 pivots about itself to rotate the input shaft118. The drive arm 172 defines two distal ends 174, each engaging one ofthe tabs 162. The distal ends 174 are moved when the drive abutments 163of the tabs 162 are engaged thereby. As with the first embodiment, thedistance between the tabs 162 and the first 150 and second 152 cams isless than the distance between the tab abutments 163 and the distal end174 of the drive arm 172. Again, this allows the first 150 and second152 cams to disengage from the cylinder 130 allowing the drive arm 172to be unlocked before the drive arm 172 is moved.

The drive arm 172 includes a plurality of fulcrums 176 that provide twofunctions. The first function of the fulcrums 176 is to provide asurface about which the first 150 and second 152 cams can rock orrotate. The second function of the fulcrums 176 is to provide a surfaceinterconnecting the drive arms 172 to the cylinder 130 which the first150 and second 152 cams can be forced between to prevent movement of theadjuster mechanism 16. As in the first embodiment, a second pair offirst and second cams are shown in the embodiment and are indicated byreference characters 150′ and 152′, respectively. Positioning springs178, 180 maintain the space between cams 150, 152′ and 152, 150′.

Referring to FIG. 7, a ratchet mechanism 182 is generally shown. Theratchet mechanism 182 includes a ratchet 184 that is circular in shape.The pawls 168, 169 engage the ratchet 184 in a selective manner to lockthe input shaft 118 in position while the lever 119 is reciprocated backto a neutral position for further movement. As may be seen in FIG. 7,each of the pawls 168, 169 include a first head 186, 188 and a secondhead 190, 192. The first 186, 188 and second 190, 192 pawl heads arecomplementary about their respective offset axes 194, 196. Each offsetaxis 194, 196 is parallel to and spaced from the input shaft 118. Thecomplementary design of the pawls 168, 169 allow for each to operate inboth directions in which the lever 119 may be moved to move the adjustermechanism 16 up or down. The pawl springs 170, 171 engage the pawlspring cam surfaces 165, 167 to maintain the pawls 168, 169 in anon-actuated state where neither of the pawls 168, 169 engage theratchet 184.

Referring to FIG. 8, the second embodiment of the clutch assembly 120 isgenerally shown where both the actuator 160 and the ratchet mechanism182 are in a non-actuated state. The cams 150, 152 are locked againstthe cylinder 130. The distal ends 174 of the drive arm 172 are notengaged by either of the drive abutments 163. Likewise, the pawls 168,169 are not engaging the ratchet 184.

Referring to FIG. 9, a simplified view of the ratchet mechanism 182 isshown wherein the second heads 190, 192 of the pawls 168, 169 haveengaged the ratchet 184. Each of the pawl heads 186–192 have a pluralityof teeth that engage the teeth of the ratchet 184. The pawl geometriesare designed to be self-locking to prevent slip between the pawls 168,169 and the ratchet 184.

Referring to FIG. 10, the clutch assembly 120 is shown with the tabs 162abutting the cams 152, 152′. This allows the actuator 160 to unlock thedrive arm 172 prior to the actuator 160 attempting to move the drive arm172. The profile of the cams 150, 150′ allow for slippage when theactuator 160 is pivoting in the direction shown in FIG. 10. Therefore,with the second cams 152, 152′ unlocked and the first cams 150, 150′slipping, the actuator 160 can move with respect to the cylinder 130.

Referring to FIG. 11, it is shown where the actuator 160 has moved toclose the gap between the drive abutments 163 and the distal ends 174 ofthe drive arm 172. In this position, the drive arm 172 remains unlockedand is moved by the drive abutments 163. By moving the drive arm 172,the input shaft 118 of the adjuster mechanism 16 is moved to adjust theheight of the seat cushion 12. It should be appreciated by those skilledin the art that actuation of the actuator 160 in the opposite directionwill provide unlocking of the drive arm 172 and rotation thereof in adirection opposite that shown in FIGS. 10 and 11 and, as such, it willnot be explained in detail herein.

Referring to FIG. 4, the actuator 160 is fixedly secured to a fixedportion 198 of the adjuster mechanism 116. The adjuster mechanism 116includes a rack 200. The rack 200 includes a plurality of rack teeth 202defined along an edge 204 of the rack 200. The rack 200 is forwardly andrearwardly displaceable with respect to the fixed portion 198. The rack200 is operatively coupled to the seat cushion 12 for moving the seatcushion 12 upwardly or downwardly relative to the floor 5 in response tothe forward or rearward displacement, respectively, or the rack 200.

The input shaft 118 includes a distal end 206 projecting axially fromthe actuator 160. A gear 208 is fixedly secured to the distal end 206 ofthe input shaft 118. The gear 208 is engaged with the plurality of rackteeth 202 in the rack 200 for moving the rack 200 forwardly orrearwardly in response to corresponding rotation of the input shaft 118via operation of the actuator 160, as described above.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology, which has been used, is intended tobe in the nature of words of description rather than of limitation.

Many modification and variations of the present invention are possiblein light of the above teachings. It is, therefore, to be understood thatwithin the scope of the appended claims, the invention may be practicedother than as specifically described.

1. A clutch assembly for actuating an input shaft of an adjustermechanism in a seat for a motor vehicle, said clutch assemblycomprising: a cylinder fixedly secured to the seat, said cylinderincluding an inner wall; a mobile flange fixedly secured to the inputshaft for rotating the input shaft with respect to said cylinder, saidmobile flange including a periphery and a plurality of outwardlyextending teeth extending about a portion thereof; a cam mechanismselectively engagable with said inner wall of said cylinder to preventmovement of said mobile flange and the input shaft relative to saidcylinder and operatively assembled to said mobile flange for movement inand out of engagement with said cylinder; an actuator operativelyinterconnected to said cylinder for movement relative to said mobileflange, said actuator including a tab engagable with said cam mechanismduring movement of said actuator relative to said mobile flange to movesaid cam mechanism out of engagement with said cylinder to release theadjuster mechanism allowing movement of the seat; and wherein said cammechanism includes first and second cams, each disposed adjacent saidtab on opposite sides thereof such that said tab engages said first camwhen said actuator pivots in first direction and said tab engages saidsecond cam when said actuator pivots in a second direction.
 2. A clutchassembly as set forth in claim 1 wherein said actuator includes aplurality of inwardly extending teeth engagable with said plurality ofoutwardly extending teeth.
 3. A clutch assembly as set forth in claim 2wherein said tab is spaced from said first and second cams apredetermined distance.
 4. A clutch assembly as set forth in claim 3wherein each of said plurality of outwardly directed teeth and each ofsaid inwardly directed teeth define a gap wider than said predetermineddistance.
 5. A clutch assembly as set forth in claim 1 including a drivearm fixedly secured to the input shaft and pivotal thereabout such thatpivotal movement of said drive arm rotates the input shaft.
 6. A clutchassembly as set forth in claim 5 wherein said drive arm includes adistal end engagable with said tab and to be driven thereby.
 7. A clutchassembly as set forth in claim 6 wherein said drive arm further includesa plurality of fulcrums allowing said first and second cams to rockthereabout.
 8. A clutch assembly as set forth in claim 7 including aratcheting mechanism to prevent movement of the seat when said actuatorreciprocates back to a steady state position from an extended position.9. A clutch assembly as set forth in claim 8 wherein said ratchetingmechanism includes a circular ratchet fixedly secured to the inputshaft.
 10. A clutch assembly as set forth in claim 9 wherein saidratcheting mechanism includes a pawl pivotal about an offset axisparallel to and spaced from the input shaft.
 11. A clutch assembly asset forth in claim 10 wherein said pawl includes first and second pawlheads, said second pawl head complementing said first pawl head withrespect to said offset axis.
 12. A clutch assembly as set forth in claim11 including a pawl spring for spring biasing said pawl out ofengagement with said ratchet.
 13. A clutch assembly as set forth inclaim 12 including a race extending around said cylinder between saidcylinder and said actuator for reducing frictional forces therebetween.14. A clutch assembly as set forth in claim 13 wherein said raceincludes a plurality of ball bearings.
 15. A clutch assembly as setforth in claim 12 wherein said pawl spring extending between first andsecond pawl ends.
 16. A clutch assembly as set forth in claim 15 whereinsaid cylinder includes first and second pawl spring cam surfaces, eachof said first and second pawl spring cam surfaces receiving each of saidfirst and second pawl ends.
 17. A clutch assembly as set forth in claim16 wherein said tab includes first and second drive abutments extendingoutwardly from said tab and engagable with said drive arm to move saiddrive arm.
 18. A clutch assembly for actuating an input shaft of anadjuster mechanism in a seat for a motor vehicle, said clutch assemblycomprising: a cylinder fixedly secured to the seat, said cylinderincluding an inner wall; a mobile flange fixedly secured to the inputshaft for rotating the input shaft with respect to said cylinder; a cammechanism selectively engagable with said inner wall of said cylinder toprevent movement of said mobile flange and the input shaft relative tosaid cylinder and operatively assembled to said mobile flange formovement in and out of engagement with said cylinder; an actuatoroperatively interconnected to said cylinder for movement relative tosaid mobile flange, said actuator including a tab engagable with saidcam mechanism during movement of said actuator relative to said mobileflange to move said cam mechanism out of engagement with said cylinderto release the adjuster mechanism allowing movement of the seat; saidcam mechanism includes first and second cams, each disposed adjacentsaid tab on opposite sides thereof such that said tab engages said firstcam when said actuator pivots in first direction and said tab engagessaid second cam when said actuator pivots in a second direction; a drivearm fixedly secured to the input shaft and pivotal thereabout such thatpivotal movement of the drive arm rotates the input shaft, said drivearm including a distal end engagable with said tab to be driven therebyand a plurality of fulcrums allowing said first and second cams to rockthereabout; and a ratchet mechanism to prevent movement of the seat whensaid actuator reciprocates back to a steady state position from anextended position.